The invention relates to a rotary solenoid having a substantially cylindrical armature, the effective pole faces of which are disposed adjacent the respective ends of the armature, with the latter being adapted to be attached to a drive shaft for actuation thereby.
In electronic teleprinters and the like, the drive to the perforator and feed mechanism of an attachment perforator cannot be taken directly from the teleprinter itself, and as a result thereof, with this type of equipment the attachment perforator must be provided with special drive arrangements. In this context, such drive arrangements must, in particular, be matched to the intermittent motions produced in the operation of the punches and during the feed motion, whereby the drive should be such that it can be brought into operation at any time and has a short access time.
These conditions are met, in a particularly advantageous manner, by the utilization of rotary solenoids as the drive mechanisms. Consequently, the utilization of rotary solenoids has been proposed in which such a solenoid is provided for each punch and for the feed mechanism, the solenoid usually actuating a bell crank lever in opposition to the force of a spring.
Known rotary solenoids, for example, of type manufactured by the Harting firm, under the designation of No. 500, employ a cylindrical stator housing containing a coil in which a cylindrical armature is disposed, the effective pole faces of the housing being adjacent the ends of the armature, which in turn is attached to drive shaft. The latter is carried in bearing plates at the ends of the stator housing, the bearing plates themselves being attached to the stator housing by dowel screws. All parts, with the exception of the coil, involve machined, i.e. turned components, as a result of which the manufacture thereof is very expensive.
As the available torque in rotary armature solenoids is closely dependent upon the size of the air gap, effort is made in the design of such type of solenoids to keep such air gaps as small as possible. However, it will be appreciated that there are limits with respect to the extent to which this can be realized in practice, as a result of armature bearing tolerances. Consequently, it has heretofore been considered that the requisite accuracy could be achieved only by the use of machined, i.e. turned components.